Process for preparation of light-sensitive material containing microcapsules

ABSTRACT

A process for preparation of a light-sensitive material containing microcapsules is disclosed. The light-sensitive material comprises a light-sensitive layer provided on a support. The microcapsules are dispersed in the light-sensitive layer. The process of the present invention comprises the steps of: (1) mixing a silver halide emulsion and the reducing agent or the photopolymerization initiator with the polymerizable compound to prepare a light-sensitive composition; (2) emulsifying the composition in an aqueous medium to prepare an aqueous emulsion; (3) forming a shell around the droplets of the composition contained in the aqueous emulsion to prepare a microcapsule dispersion; (4) coagulating the aqueous medium to set the microcapsule dispersion; (5) storing the set microcapsule dispersion; (6) melting the aqueous medium to prepare a coating solution of the light-sensitive layer; and (7) coating the solution on the support. Between the steps (2) and (3), the process preferably further contains the steps of: (a) precipitating the droplets of the light-sensitive composition in the aqueous emulsion; (b) removing at least 50% of the supernatant medium from the droplets; and (c) emulsifying the droplets in an aqueous medium again.

FIELD OF THE INVENTION

The present invention relates to a process for preparation of alight-sensitive material containing microcapsules.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 4,912,011 discloses a light-sensitive material comprisinga support and a light-sensitive layer provided thereon which containssilver halide, a reducing agent, a polymerizable compound and a colorimage forming substance. The silver halide, the reducing agent, thepolymerizable compound and the color image forming substance arecontained in microcapsules (light-sensitive microcapsules) which aredispersed in the light-sensitive layer. The U.S. Patent corresponds toJapanese Patent Provisional Publications No. 61(1986) 275742 and No.61(1986)-849 and European Patent Provisional Publication No. 0203613A.

An image forming method using the light-sensitive material is alsodisclosed in U.S. Patent 4,912,011. The method comprises the steps ofimagewise exposing the light-sensitive material, and heating thelight-sensitive material. A latent image of the silver halide is formedby the exposure. The polymerizable compound is polymerized by heatingwithin the area where the latent image has been formed. Thelight-sensitive material is then pressed on an image-receiving materialto transfer the unpolymerized polymerizable compound with a color imageforming substance to the image-receiving material to form a color imageon the image-receiving material.

Further, a method of polymerizing the polymerizable compound within thearea where the latent image of the silver halide has not been formed isdisclosed in Japanese Patent Provisional Publications No.61(1986)-243449, No. 61(1986)-260241, No. 2(1990)-141756 and No. 2(1990)141757. The contents of the former two publications are described inEuropean Patent Provisional Publication No. 0202490A.

On the other hand, U.S. Pat. Nos. 4,440,846, 4,483,912 and 4,554,235disclose a light-sensitive material comprising a support and alight-sensitive layer provided thereon which contains aphotopolymerization initiator, a polymerizable compound and a colorimage forming substance. The photopolymerization initiator, thepolymerizable compound and the color image forming substance arecontained in microcapsules (light-sensitive microcapsules) which aredispersed in the light-sensitive layer. U.S. Pat. No. 4,440,846corresponds to Japanese Patent Provisional Publications No.57(1982).179836, No. 58(1983) 88739 and No. 58(1983).88740. U.S. Pat.No. 4,483,912 corresponds to Japanese Patent Provisional PublicationsNo. 59(1984)-30537 and No. 59(1984)-137944. U.S. Pat. No. 4,554,235corresponds to Japanese Patent Provisional Publication No.60(1985)-259490.

An image forming method using the photopolymerization initiatorcomprises imagewise exposing the light-sensitive material to imagewisepolymerize the polymerizable compound by the photopolymerizationinitiator. The light-sensitive material is then pressed on animage-receiving material to transfer the unpolymerized polymerizablecompound with a color image forming substance to the image-receivingmaterial to form a color image on the image-receiving material.

The above-mentioned light-sensitive materials are prepared by a processcomprising the steps of: (I) mixing a silver halide emulsion and areducing agent (U.S. Pat. No. 4,912,011 et al.) or a photopolymerizationinitiator (U.S. Pat. No. 4,440,846 et al.) with a polymerizable compoundto prepare a light-sensitive composition; (II) emulsifying thecomposition in an aqueous medium to prepare an aqueous emulsion; (III)forming a shell around the droplets of the composition contained in theaqueous emulsion to prepare a microcapsule dispersion; (IV) preparing acoating solution of the light-sensitive layer from the microcapsuledispersion and (V) coating the solution on a support.

FIGS. 3A and 3B are flowcharts schematically illustrating theconventional process for preparation of the light-sensitive materialcontaining silver halide and a reducing agent. The light-sensitivematerial shown in FIG. 3A is a preferred embodiment wherein a colorimage forming substance and a base precursor in addition to the silverhalide, the reducing agent and the polymerizable compound are containedin microcapsules. The light-sensitive material shown in FIG. 3B also isa preferred embodiment which forms a color image by using blue, greenand red sensitive microcapsules.

At the step (I), a color image forming substance (32), a solution of areducing agent (33), a dispersion of a base precursor (34) and a silveremulsion (35) are mixed with a polymerizable compound (31) to prepare alight-sensitive composition (36). At the step (II), the light-sensitivecomposition (36) is emulsified in an aqueous medium (37) to prepare anaqueous emulsion (38). At the step (III), a shell is formed around thedroplets of the composition contained in the aqueous emulsion (38) toprepare a microcapsule dispersion (39). At the step (IV), a bluesensitive microcapsule dispersion (41), a green sensitive microcapsuledispersion (42) and a red sensitive microcapsule dispersion (43) aremixed to prepare a coating solution of the light-sensitive layer (44).At the step (V), the coating solution (44) is coated on a support (45)to prepare a light-sensitive material (46).

The above-mentioned light-sensitive materials can be used for varioustechnical fields such as color photography, printing and copying (e.g.,a computer-graphic hard copy and a color copy). Accordingly, variouskinds of the light-sensitive material are required in practical use. Thedifference practical uses require different light-sensitive materials,particularly with respect to spectral sensitivity and hue of the formedcolor.

SUMMARY OF THE INVENTION

The applicants have studied the above-mentioned process for preparationof the light-sensitive material. The applicants note that theconventional process is not appropriate for mass production of variouskinds of the light-sensitive material. The applicants further notes thatan intermediate in preparation of the light-sensitive material ispreferably stored to facilitate the mass production of thelight-sensitive material.

The process for preparation of the light-sensitive material comprisesthe above-mentioned five steps of (I) to (V). Accordingly, there arefour intermediate stages, namely (I) the light-sensitive composition,(II) the aqueous emulsion of the light-sensitive composition, (III) themicrocapsules dispersion, and (IV) the coating solution of thelight-sensitive layer.

According to further study of the applicants, the microcapsuledispersion is most preferably stored to facilitate the mass productionof the light-sensitive material. However, the applicants note a problemwhen the microcapsule dispersion is stored. The specific gravity of thecore of the microcapsule (namely the light-sensitive composition) isusually more than 1. Further, the microcapsules have a relatively largeparticle size (5 to 25 m), since the above-mentioned microcapsulescontain various components. Accordingly, the microcapsules are depositedto the bottom of a vessel while the dispersion is stored. The depositedmicrocapsules adhere to each other. When the stored microcapsuledispersion is used for preparation of the light-sensitive material, theadhering microcapsules should be separated by stirring the dispersion.Some of the microcapsules are ruptured or destroyed by the separatingprocess.

Therefore, when the light-sensitive material is prepared by using thestored microcapsule dispersion, the formed image is not clear because ofthe destroyed microcapsules. Particularly, a stain is observed on theimage, and the minimum density of the image is high.

An object of the present invention is to provide a process forpreparation of a light-sensitive material which forms a clear image,even if the material is prepared by using a stored microcapsuledispersion.

There is provided by the present invention a process for preparation ofa light-sensitive material comprising a support and a light-sensitivelayer which contains silver halide, a reducing agent and anethylenically unsaturated polymerizable compound, said silver halide,said reducing agent and said polymerizable compound being contained inmicrocapsules which are dispersed in the light sensitive layer, whereinthe process comprises the steps of:

(1) mixing a silver halide emulsion and the reducing agent with thepolymerizable compound to prepare a light-sensitive composition;

(2) emulsifying the composition in an aqueous medium to prepare anaqueous emulsion;

(3) forming a shell around the droplets of the composition contained inthe aqueous emulsion to prepare a microcapsule dispersion;

(4) coagulating the aqueous medium to set the microcapsule dispersion;

(5) storing the set microcapsule dispersion;

(6) melting the aqueous medium to prepare a coating solution of thelight-sensitive layer; and

(7) coating the solution on the support.

There is also provided by the invention a process for preparation of alight-sensitive material comprising a support and a light-sensitivelayer which contains a photopolymerization initiator and anethylenically unsaturated polymerizable compound, saidphotopolymerization initiator and said polymerizable compound beingcontained in microcapsules which are dispersed in the light sensitivelayer, wherein the process comprises the steps of:

(1) mixing the photopolymerization initiator with the polymerizablecompound to prepare a light-sensitive composition;

(2) emulsifying the composition in an aqueous medium to prepare anaqueous emulsion;

(3) forming a shell around the droplets of the composition contained inthe aqueous emulsion to prepare a microcapsule dispersion;

(4) coagulating the aqueous medium to set the micro capsule dispersion;

(5) storing the set microcapsule dispersion;

(6) melting the aqueous medium to prepare a coating solution of thelight-sensitive layer; and

(7) coating the solution on the support.

In the case that the shell of the microcapsules is made of anamino-aldehyde resin, between the above-mentioned steps (2) and (3), theprocess preferably further contains the steps of:

(a) precipitating the droplets of the light-sensitive composition in theaqueous emulsion;

(b) removing at least 50% of the supernatant medium from the droplets;and

(c) emulsifying the droplets in an aqueous medium again.

The above-mentioned deposition of the microcapsules can be prevented bystirring the microcapsule dispersion or shaking the vessel containingthe dispersion while the dispersion is stored. It requires a specificapparatus to stir the dispersion or to shake the vessel. Further, someof the microcapsules are ruptured or destroyed by stirring thedispersion or shaking the vessel.

The applicants found that the microcapsule dispersion 15 can bepreserved without causing the deposition and destroying themicrocapsules by the above-mentioned steps (4) to (6). Therefore, thelight-sensitive material prepared according to the present inventionforms a clear image, though the material is prepared by using a storedmicrocapsule dispersion. Further, the process of the invention using thestored microcapsule dispersion is advantageous to the mass production ofvarious kinds of the light-sensitive material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart schematically illustrating the characteristicsteps (4) to (6) of the present invention.

FIG. 2 is a flowchart schematically illustrating the steps (a) to (c) ofthe preferred embodiment of the present invention.

FIGS. 3A and 3B are flowcharts schematically illustrating theconventional process for preparation of the light-sensitive material.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is characterized in the abovementioned steps (4),(5) and (6).

FIG. 1 is a flowchart schematically illustrating the characteristicsteps (4) to (6) of the present invention.

The microcapsule dispersion (11) shown in FIG. 1 is prepared by thesteps (1) to (3) of the present invention. The dispersion (11)corresponds to the microcapsule dispersion (39) shown FIG. 3A. In otherwords, the steps (1) to (3) of the present invention are the same as thesteps (I) to (III) of the conventional process shown in FIG. 3A. At thestep (4), the aqueous medium contained in the microcapsule dispersion(11) is coagulated to set the dispersion. As is shown in FIG. 1, theaqueous medium is preferably coagulated by the steps of: (4.1) adding anaqueous polymer (12) as a gelation agent to the microcapsule dispersion(13); and (4.2) cooling the dispersion containing the aqueous polymer(13). The dispersion containing the polymer (13) is cooled in arefrigerator (15) to set the dispersion (16).

At the step (5), the set microcapsule dispersion is stored in therefrigerator (15).

At the step (6), the aqueous medium is melted by heating. the storeddispersion (16).

Thus obtained dispersion (17) can be used to prepare a coating solutionof the light-sensitive layer. For example, a blue sensitive microcapsuledispersion, a green sensitive microcapsule dispersion and a redsensitive microcapsule dispersion may be mixed to prepare a coatingsolution of the light-sensitive layer, as is shown in FIG. 3B. At thestep (7), the coating solution is coated on a support to prepare alight-sensitive material. The step (7) of the present invention is thesame as the steps (V) of the conventional process shown in FIG. 3B.

The characteristic steps (4) to (6) of the present invention aredescribed in more detail.

An aqueous polymer is preferably used as a gelation agent at the step(4) as is mentioned above. Examples of the aqueous gelation polymerinclude a polysaccharide (e.g., carrageenan, sodium alginate, agar,gellan gum, furcellaran, pectin, agarose) and a protein (e.g., gelatin).In the case that the shell of the microcapsules is made of anamino-aldehyde resin (e.g., melamine-formaldehyde resin,urea-formaldehyde resin), the polysaccharide (containing no amino group)is preferred to the protein (containing an amino group). Theamino-aldehyde resin may react with the amino group contained in theprotein to cause an irreversible coagulation of the microcapsuledispersion. The coagulation at the step (4) must be reversible becausethe aqueous medium is melted at the step (6) to use the dispersion inpreparation of the coating solution of the light-sensitive layer.Carrageenan, gellan gum and furcellaran are particularly preferredaqueous gelation polymers.

The amount of the gelation agent depends on the nature of the agent, thetemperature and time required for the coagulation and the strength ofthe coagulated medium required for the storage. The gelation agent ispreferably used in the microcapsule dispersion in an amount of 0.01 to10 weight %. The gel point of the aqueous medium is a temperaturepreferably in the range of 0° C. to 40° C., and more preferably in therange of 5° C. to 30° C.

After the aqueous gelation polymer is added to the microcapsuledispersion, the mixture is preferably stirred at an elevated temperature(higher than the gel point) to make a uniform dispersion. The dispersionis then quickly cooled (lower than the gel point) to set themicrocapsule dispersion.

The set microcapsule dispersion is then stored at a low temperature(lower than the gel point). The microcapsule dispersion can be storedfor not more than 90 days (preferably for not more than 30 days) in arefrigerator.

The stored microcapsule dispersion is then used for preparation of thecoating solution of the light-sensitive layer. The required amount ofthe microcapsule dispersion is preferably weighed at the stored stage.By only melting the aqueous medium, a uniform microcapsule dispersioncan be easily obtained without rupturing the microcapsules. The aqueousmedium is melted preferably by heating the stored dispersion (higherthan the gel point).

The process of the present invention preferably further contains someadditional steps between the above-mentioned steps (2) and (3) in thecase that the shell of the microcapsules is made of an amino-aldehyderesin. The additional steps comprise: (a) precipitating the droplets ofthe light-sensitive composition in the aqueous emulsion; (b) removing atleast 50% of the supernatant medium from the droplets; and (c)emulsifying the droplets in an aqueous medium again.

According to study of the applicant, the aqueous emulsion prepared atthe step (2) contains small droplets (having a droplet size of 1 to 3μm) and other irregular particles in addition to the regular dropletsrequired for preparation of the microcapsules (having a droplet size of5 to 25 μm). The applicants found that the small droplets and theirregular particles are obstacles to formation of an amino-aldehyderesin shell around the regular droplets at the step (3). Using theabove-mentioned additional steps (a) to (c), the small droplets and theirregular particles are removed with the supernatant medium. Therefore,the light-sensitive material prepared according to the processcontaining the additional steps forms a more clear image.

FIG. 2 is a flowchart schematically illustrating the steps (a) to (c) ofthe preferred embodiment of the present invention.

The aqueous emulsion (21) shown in FIG. 2 is prepared by the steps (1)and (2) of the present invention. The emulsion (21) corresponds to theaqueous emulsion (38) shown in FIG. 3A.

At the step (a), the droplets of the light-sensitive composition in theaqueous emulsion (21). are precipitated.

The specific gravity of the light-sensitive composition is usually morethan 1. Accordingly, the droplets may be naturally precipitated by onlyleaving the aqueous emulsion. However, the emulsion is preferablydiluted with water (which may contain a water-soluble polymer) toaccelerate the precipitation. The precipitation is accelerated as thedilution is increased. On the other hand, coagulation of the droplets iscaused when the emulsion is highly diluted. The dilution is preferablyin the range of 1.5 to 50.

Centrifugation may be used to accelerate the precipitation. Aprecipitating agent may also be used so long as the precipitateddroplets can be emulsified again at the step (c).

At the step (b), the supernatant medium (the small droplets and theirregular particles) is removed from the droplets (22). As is shown inFIG. 2, it is not necessary to remove all of the supernatant medium. Inthe present invention, it is sufficient to remove at least 50%(preferably at least 80%) of the medium.

At the step (c), the remaining droplets (23) are emulsified again in anaqueous medium (24) to obtain an aqueous dispersion, which is free fromthe small droplets and the irregular particles.

After the step (c), an amino-aldehyde resin shell is formed around theregular droplets at the step (3). Then, the prepared amino-aldehydemicrocapsule dispersion is treated with the characteristic steps (4) to(6) of the present invention.

The light-sensitive material prepared by the present invention isdescribed below.

In the first embodiment of the present invention, silver halide, areducing agent and an ethylenically unsaturated polymerizable compoundare contained in microcapsules. In the second embodiment of theinvention, a photopolymerization initiator and an ethylenicallyunsaturated polymerizable compound are contained in the microcapsules.The components of the light-sensitive material are described below.

Examples of the silver halide employable for the light-sensitivematerial include silver chloride, silver bromide, silver iodide, silverchlorobromide, silver chloroiodide, silver iodobromide and silverchloroiodobromide in the form of grains.

The silver halide grains may be of various crystal forms, for example, aregular crystal form such as hexahedron, octahedron or tetradecahedron,an irregular form such as spherical form or tubular form, a form havingcrystalline defect such as a twinning plane, and a mixed form thereof.

The silver halide grains may be extremely small sized grains having agrain diameter of not more than 0.01 μm, or may be relatively largesized grains having a grain diameter of projected area up to 10 μm. Thesilver halide emulsion may be a polydispersed emulsion or amonodispersed emulsion described in U.S. Pat. Nos. 3,574,628 and3,655,394, and U.K. Patent No. 1,413,748.

A tubular grain having an aspect ratio of not less than approx. 5 can bealso employed. The tubular silver halide grains can be easily preparedby processes described in Gutoff, "Photographic Science and Engineering,Vol. 14, pp. 248-257 (1970)", U.S. Pat. Nos. 4,434,226, 4,414,310,4,433,048 and 4,439,520, and U.K. Patent No. 2,112,157.

As for the crystal structure of the silver halide grains, the individualgrains may have a homogeneous halogen composition or a heterogeneoushalogen composition in which the composition varies from the outersurface portion to the inside portion, or may be a multi-layerstructure. Otherwise, the silver halide grains may be bonded with othersilver halide grains having different halogen composition throughepitaxial bonding, or may be bonded with compounds other than the silverhalide such as silver rhodanate and lead oxide. Two or more kinds ofsilver halide grains which differ in halogen composition, crystal habit,grain size, and/or other features from each other can be employed incombination.

The silver halide photographic emulsions employable in thelight-sensitive material of the invention can be prepared by processesdescribed, for example, in "Research Disclosure (RD), No. 17,643, pp.22-23 (December 1978), (Emulsion preparation and types) and No. 18,716,p. 648.

The silver halide emulsion is generally used after subjecting it tophysical ripening, chemical ripening and spectral sensitization. Variousadditives employable in those stages are described in ResearchDisclosure, No. 17,643 and No. 18,716. The relevant parts in theliterature are described below in the form of a table.

Conventional photographic additives employable in the invention are alsodescribed in the above-mentioned Research Disclosure, and the relevantparts in the literature are also shown in the following table.

    ______________________________________                                        Additives         RD 17,643  RD 18,716                                        ______________________________________                                        Chemical sensitizing agent                                                                      p. 23      p. 648 (right                                                                 side)                                            Sensitivity-increasing agent p. 648 (right                                                                 side)                                            Spectral sensitizing agent                                                                      p. 23-24   p. 648 (right                                    and Supersensitizing agent   side)-p. 649                                                                  (right side)                                     Anti-fogging agent and Sta-                                                                     p. 24-25   p.649 (right                                     bilizer                      side)                                            ______________________________________                                    

It is preferred to use silver halide grains having a relatively lowfogging value.

For uniformly incorporating the silver halide into microcapsules, acopolymer composed of a hydrophilic repeating unit and a hydrophobicrepeating unit is preferably dissolved in the polymerizable compound.

The reducing agent employable in the light-sensitive material of theinvention has a function of reducing the silver halide and/or a functionof accelerating (or restraining) polymerization of the polymerizablecompound. There are known various reducing agents having theabovementioned functions. Examples of such reducing agents includehydroquinones, catechols, p-aminophenols, p-phenylenediamines,3-pyrazolidones, 3-aminopyrazoles, 4-amino-5-pyrazolones,5-aminouracils, 4,5-dihydroxy-6 aminopyrimidines, reductones,aminoreductones, o- or p-sulfonamidophenols, o- orp-sulfonamidonaphthols, 2,4-disulfonamidophenols,2,4-disulfonamidonaphthols, o- or p-acyl aminophenols,2-sulfonamidoindanones, 4-sulfonamido-5-pyrazolones,3-sulfonamidoindoles, sulfonamidopyrazolobenzimidazoles,sulfonamidopyrazolotriazoles, α-sulfonamidoketones and hydrazines.

By adjusting the kind, amount of the above reducing agent, thepolymerizable compound can be polymerized within the area where a latentimage of the silver halide has been formed or has not been formed. In asystem wherein the polymerizable compound is polymerized within the areawhere a latent image of the silver halide has not been formed,1-phenyl-3-pyrazolidones, hydroquinones and sufonamidophenols areparticularly preferred as the reducing agent.

Various reducing agents having the above-mentioned functions (includingcompounds referred to as developing agent, hydrazine derivative) aredescribed in T. James, "The Theory of the Photographic Process", 4thedition, pp. 15 291.334 (1977), Research Disclosure Vol. 170, No. 17029,pp. 9.15 (June 1978), and Research Disclosure Vol. 176, No. 7643, pp.22-31 (December 1978). Further, there can be also employed a reducingagent precursor capable of releasing a reducing agent under heating orin contact with a base. Also in the light-sensitive material of theinvention, various reducing agents and reducing agent precursors can beeffectively employed. Thus, "the reducing agent(s)" in the presentspecification means to include all of the reducing agents and reducingagent precursors described in the publications.

The reducing agent having a basic nature can be used in the form of asalt with an appropriate acid. The reducing agents can be used singly orin combination. In the case that two or more reducing agents are used incombination, certain interactions between the reducing agents may beexpected. One of the interactions is for acceleration of reduction ofsilver halide (and/or an organic silver salt) through so-calledsuper-additivity. Other interaction is for a chain reaction in which anoxidized state of one reducing agent formed by a reduction of silverhalide (and/or an organic silver salt) induces or inhibits thepolymerization of the polymerizable compound via oxidation-reductionreaction with other reducing agent. Both interactions may occursimultaneously. Thus, it is difficult to determine which of theinteractions has occurred in practical use.

Concrete examples of the above-mentioned reducing agents are as follows.##STR1##

The reducing agent can be used in the light-sensitive material in anamount of wide range, but generally the amount thereof is in the rangeof 0.1 to 1,500 mole %, preferably in the range of 10 to 300 mole %,based on the amount of the silver salt.

There is no specific limitation with respect to the color image formingsubstance, and various kinds of substances are available. Examples ofthe color image forming substance include colored substance (i.e., dyesand pigments) and non-colored or almost non-colored substance (i.e.,color former or dye. or pigment precursor) which develops to give acolor by an external energy (e.g., heating, pressing or lightirradiation) or by other components (i.e., color developer).

In the present invention, the color image forming substance preferablyis a colored substance such as a dye or a pigment. A pigment isparticularly preferred.

As the pigment used in the invention, there can be mentioned not onlythose commercially available but also those described in variousliteratures such as "Handbook of Color Index (C. I.)", Nippon GanryoGijutsu Kyokai (ed.), "New Handbook of Pigments (1977)", CMC Shuppan(ed.), "New Application and Technique of Dyes (1986)", and CMC Shuppan(ed.), "Printing Ink Technique (1984)".

The pigments can be classified based on the color difference into whitepigment, black pigment, yellow pigment, orange pigment, brown pigment,red pigment, violet pigment, blue pigment, green pigment, fluorescentpigment, metallic powder pigment, and polymeric linking dyestuff.Examples of a pigment include insoluble azo pigment, azolake pigment,condensed azo pigment, chelate azo pigment, phthalocyanine pigment,anthraquinone pigment, perylene and perynone pigment, thioindigopigment, quinacridone pigment, dioxadine pigment, isoindolinone pigment,quinophthalone pigment, color lake pigment, azine pigment, nitrosopigment, nitro pigment, natural pigment, fluorescent pigment andinorganic pigment.

The pigment particles are preferably surface treated to be lipophilic.The methods of surface treatment include a method having the step ofcoating with a resin or a wax, a method having the step of attaching ofa surface active agent or a method having the step of connecting anactive substance (e.g., a silane coupling agent, an epoxy compound andpolyisocyanate) onto the surface of the pigment. The methods aredisclosed in "Nature and Application of Metallic Soap", Saiwai Shobo(ed.); "Printing Ink Technique", CMC Shuppan (ed. 1984); and "NewApplication and Technique of Pigment", CMC Shuppan (ed. 1986).

The diameter of the pigment particles preferably is in the range of 0.01to 10 μm, more preferably 0.05 to 1 μm in the measurement after theparticles are dispersed in the polymerizable compound.

The pigment is preferably used in an amount of 5 to 60 parts by weight,based on 100 parts by weight of the polymerizable compound. The pigmentparticles can be dispersed in the same manner as in a known dispersingtechnique such as preparation of ink or toner. Various dispersingdevices are available. Examples of the dispersing device include a sandmill, an attritor, a pearl mill, a supermill, a ball mill, an impeller,a disperser, a KD mill, a colloid mill, a dynatron, a three-rolls milland a pressure kneader. The dispersing devices are described in "NewApplication and Technique of Pigment", CMC Shuppan (ed. 1986).

The polymerizable compounds used in the light-sensitive material arecompounds having an ethylenically unsaturated group.

Examples of the compounds having an ethylenic unsaturated group whichcan be used for the light-sensitive material include acrylic acids,salts of acrylic acids, acrylic esters, acrylamides, methacrylic acid,salts of methacrylic acids, methacrylic esters, methacrylamides, maleicanhydride, maleic esters, itaconic esters, styrenes, vinyl ethers, vinylesters, N-vinyl heterocyclic compounds, allyl ethers, allyl esters, andderivatives thereof.

Examples of the acrylic esters include n-butyl acrylate, cyclohexylacrylate, 2-ethylhexyl acrylate, benzyl acrylate, furfuryl acrylate,ethoxyethoxyethyl acrylate, tricyclodecanyl acrylate,nonylphenyloxyethyl acrylate, 1,3-dioxolan acrylate, hexanedioldiacrylate, butanediol diacrylate, neopentylglycol diacrylate,tricyclodecandimethylol diacrylate, trimethylolpropane triacrylate,pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate,dipentaerythritol hexacrylate, diacrylate of polyoxyethylenatedbisphenol A, 2 (2-hydroxy-1,1-dimethylethyl)5-hydroxymethyl-5-ethyl-1,3-dioxane diacrylate,(2-hydroxy-1,1-dimethylethyl) 5,5-dihydroxymethyl-1,3-dioxanetriacrylate, triacrylate of propyleneoxide addition product oftrimethylolpropane, polyacrylate of hydroxypolyether, polyester acrylateand polyurethane acrylate.

Examples of the methacrylic esters include methyl methacrylate, butylmethacrylate, ethylene glycol dimethacrylate, butanediol dimethacrylate,neopentylglycol dimethacrylate, trimethylolpropane trimethacrylate,pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate anddimethacrylate of polyoxyalkylenated bisphenol A.

The polymerizable compounds can be used singly or in combination of twoor more compounds. Further, polymerizable compounds in which apolymerizable functional group such as a vinyl group or a vinylidenegroup is introduced into a chemical structure of the above-describedreducing agent can be also employed as the polymerizable compound.

The base precursor used in the present invention includes variousinorganic or organic compounds, and is classified into decarboxylationtype, thermal decomposition type, reaction type and complexsalt-formation type.

The base precursor preferably is a salt of an organic base and an acidwhich decarboxylates under heating or a compound which release a baseunder heating.

The base precursor used in the invention preferably releases a base at atemperature in the range of 50° C. to 200° C., and more preferably 80°C. to 180° C.

The base precursor preferably has a solubility in water of not more than1% at 25° C. to be incorporated into microcapsules.

A preferred base precursor is composed of a salt of an organic base witha carboxylic acid. The organic base preferably is a diacidic, triacidicor tetraacidic base which composed of two to four amidine or guanidinemoieties and at least one residue of a hydrocarbon or a heterocyclicring as a linking group of the amidine or guanidine moieties.

The amidine moiety corresponds to an atomic group formed by removing oneor two hydrogen atoms from the compound having the formula (I). ##STR2##

In the formula (I), each of R¹¹, R¹², R¹³ and R¹⁴ independently is amonovalent group selected from the group consisting of hydrogen, analkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, anaralkyl group, an aryl group and a heterocyclic group, each of which mayhave one or more substituent group; and any two of R¹¹, R¹², R¹³ and R¹⁴may be combined together to form a five-membered or six-memberednitrogen containing heterocyclic ring.

The guanidine moiety corresponds to an atomic group formed by removingone or two hydrogen atoms from the compound having the formula (II).##STR3##

In the formula (II , each of R²¹, R²², R²³, R²⁴ and R²⁵ independently isa monovalent group selected from the group consisting of hydrogen, analkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, anaralkyl group, an aryl group and a heterocyclic group, each of which mayhave one or more substituent group; and any two of R²¹, R²², R²³, R²⁴and R²⁵ may be combined together to form or six-memberednitrogen-containing heterocyclic ring.

Examples of the base precursor are shown below. ##STR4##

In the second embodiment of the present invention, a photopolymerizationinitiator is contained in microcapsules in place of the silver halideand the reducing agent.

Examples of the photopolymerization initiators include α-alkoxyphenylketones, polycyclic quinones, benzophenones and substitutedbenzophenones, xanthones, thioxanthones, halogenated compounds (e.g.,chlorosulfonyl and chloromethyl polycyclic aromatic compounds,chlorosulfonyl and chloromethyl heterocyclic compounds, chlorosulfonyland chloromethyl benzophenones, and chlorosulfonyl and chloromethylfluorenones), haloalkanes, α-halo-αphenylacetophenones, photo-reducingdye reducing redox couples, halogenated paraffins (e.g., brominated orchlorinated paraffin), benzoalkyl ethers, rofindimer-mercapto compoundcouples and organic boron compound anionic salts of organic cationiccompounds.

Preferred examples of the photopolymerization initiators includebenzoisobutyl, 2,2-dimethoxy-2-phenylacetophenone, 9,10-anthraquinone,benzophenone, Michler's ketone, 4,4,-diethylaminobenzophenone, xanthone,chloroxanthone, thioxanthone, chlorothioxanthone,2,4-diethylthioxanthone, chlorosulfonylthioxanthone,chlorosulfonylanthraquinone, chloromethylanthraquinone,chloromethylbenzothiazole, chlorosulfonylbenzoxazole,chloromethylquinoline, chloromethylbenzophenone,chlorosulfonylbenzophenone, fluorenone, carbon tetrabromide,benzoisobutylether, benzoynisopropylether and combination of2,2,-bis(o-chlorophenyl)-4,4,'5,5'-tetraphenylbiimidazole and 2-mercapto5-methylthio-1,3,4-thiadiazole.

As the photopolymerization initiator, the above-mentioned compounds canbe used singly or in combination of two or more kinds.

In the second embodiment of the invention, the photopolymerizationinitiator is preferably used in an amount of 0.5 to 30% by weight, morepreferably 2 to 20% by weight, based on the amount of the polymerizablecompound. There is no specific limitation on the preparation ofmicrocapsules, and any known processes can be employed. Examples of theprocesses for preparing microcapsules include a process utilizingcoacervation of hydrophilic wallforming materials (U.S. Pat. Nos.2,800,457 and 2,800,458); an interfacial polymerization process (U.S.Pat. No. 3,287,154, U.K. Patent No. 990,443, and Japanese PatentPublications No. 38(1963)-19574, No. 42(1967) 446 and No. 42(1967)-771);a process utilizing precipitation of polymers (U.S. Pat. Nos. 3,418,250and 3,660,304); a process of using isocyanate-polyol wall-materials(U.S. Pat. No. 3,796,669); a process of using isocyanate wall-materials(U.S. Pat. No. 3,914,511); and a process of using amino-aldehyde resins(U.S. Pat. Nos. 4,001,140, 4,087,376, 4,089,802 and 4,025,455, andJapanese Patent Provisional Publications No. 62(1987)-209439, No.64(1989)-91131 and No. 1(1989)-154140).

Examples of the amino-aldehyde resins include an urea-formaldehyderesin, an urea-formaldehyde-resorcinol resin, a melamine-formaldehyderesin, an acetoguanamine-formaldehyde resin and abenzoguanamine-formaldehyde resin. Further, examples of the processesfor preparing microcapsules include an in situ process utilizingpolymerization of monomers (Japanese Patent Publication No.36(1961)-9168 and Japanese Patent Provisional Publication No. 51(1976)9079); a polymerization dispersing and cooling process (U.K. Patents No.927,807 and No. 965,074); and a spray-drying process (U.S. Pat. No.3,111,407 and U.K. Patent No. 930,422).

A process for encapsulating oily droplets of the polymerizable compoundis not limited to the above-mentioned ones, but a process of emulsifyingcore materials and then forming a polymeric membrane as a microcapsuleshell over the core material is particularly preferred. Examples of theshell material include a polyamide resin and/or a polyester resin, apolyurea resin and/or a polyurethane resin, gelatin, an epoxy resin, acomplex resin containing a polyamide resin and a polyurea resin, acomplex resin containing a polyurethane resin and a polyester resin. Amelamine-formaldehyde resin, of which fine microcapsules can be made, isparticularly preferred in the invention.

The microcapsule having a polymer shell of a polymeric compound around afilm composed of a reaction product of a water-soluble polymer having asulfinyl group and a polymerizable compound having an ethylenicunsaturated group is preferred.

In the case that aminoaldehyde resins are used for microcapsules, theamount of residual aldehyde is preferably regulated to be below acertain value.

A mean grain size of microcapsules is preferably within the range of 3to 20 μm. It is preferred that the grain sizes of microcapsules behomogeneously dispersed in the range above a certain value. The ratiobetween the thickness and the grain size of a microcapsule is preferablywithin a certain range.

In the case that a silver halide is contained in microcapsules, theabove-described mean grain size of the silver halide is preferably notmore than one fifth of the mean grain size of microcapsules, and morepreferably it is not more than one tenth. A homogeneous and smooth imagecan be obtained by regulating the mean grain size of the silver halidenot to be more than one fifth of the mean grain size of microcapsules.

In the case that a silver halide is contained in microcapsules, thesilver halide is preferably contained within the shell of themicrocapsule.

In preparation of the microcapsules, a base precursor can be directlydispersed in a polymerizable compound. However, it is particularlypreferred that a base precursor is dispersed in water, and thedispersion is then emulsified in a polymerizable compound. In this case,a nonionic or amphoteric water soluble polymer is preferably dissolvedin water in which the base precursor is dispersed.

Examples of the nonionic water soluble polymer include polyvinylalcohol, polyvinyl pyrrolidone, polyacrylamide, polymethylvinyl ether,polyacryloylmorpholine, polyhydroxyethylacrylate,polyhydroxyethylmethacrylate-co-acrylamide, hydroxyethyl cellulose,hydroxypropyl cellulose and methyl cellulose. An example of theamphoteric water soluble polymer is gelatin.

The water soluble polymer is preferably used in an amount of 0.1 to 100weight % based on the amount of the base precursor, and more preferably1 to 50 weight %. The base precursor is preferably contained in thedispersion in an amount of 5 to 60 weight %, and more preferably of 10to 50 weight %. The base precursor is preferably used in an amount of 2to 50 weight % based on the amount of the polymerizable compound, andmore preferably 5 to 30 weight %.

When a shell of a microcapsule is formed by dispersing an oily liquidcontaining a base precursor to an aqueous medium in the process forpreparing the light-sensitive microcapsules, a nonionic or anionic watersoluble polymer is preferably contained in the aqueous medium. Theamount of oily liquid is preferably within the range of 10 to 120weight. %, more preferably 20 to 90 weight. %, based on the amount ofthe aqueous medium.

Examples of the nonionic water soluble polymer include polyvinylalcohol, polyvinyl pyrrolidone, polyacrylamide, polymethylvinyl ether,polyacryloylmorpholine, polyhydroxyethylacrylate,polyhydroxyethylmethacrylate-co-acrylamide, hydroxyethyl cellulose,hydroxypropyl cellulose and methyl cellulose. Examples of the anionicwater soluble polymer include polystyrenesulfinic acid, a salt of acopolymer of styrenesulfinic acid, a salt of polystyrenesulfonic acid, acopolymer of styrenesulfonic acid, a salt of polyvinyl sulfate, a saltof polyvinylsulfonic acid, a copolymer of maleic anhydride and styrene,and a copolymer of maleic an hydride and isobutylene.

The aqueous medium preferably contains the anionic water soluble polymerin an amount of 0.01 to 5 weight %, and more preferably 0.1 to 2 weight%. It is particularly preferred to use a water soluble polymer having afew sulfinic groups together with a nonionic water soluble polymer. Ahydrophilic compound is preferably dissolved in a polymerizable compoundto reduce the solubility of the base precursor in the polymerizablecompound. Examples of the hydrophilic group of the compound include--OH, --SO₂ NH₂, --CONH₂ and --NHCONH₂. Examples of the hydrophiliccompound include polyethylene glycol, polypropylene glycol, benzoicamide, cyclohexylurea, octyl alcohol, dodecyl alcohol, stearyl alcoholand stearamide.

Examples of the materials used for the preparation of the supportinclude glasses, ordinary papers, fine paper, coat paper, cast-coatpaper, synthetic papers, metals and analogues thereof, various filmsmade of polyester, polyethylene, polypropylene, acetyl cellulose,cellulose ester, polyvinyl acetal, polystyrene, polycarbonate,polyethylene terephthalate and polyimide, and papers laminated withresin or polymer (e.g., polyethylene).

A polymer film support is particularly preferred. The thickness of thepolymer film is preferably not more than 50 μm for the efficiency ofheat conduction because the light-sensitive material is preferablyheated from the side of the support.

In the image formation, the light-sensitive material may be imagewiseexposed to light, heated and pressed on an image receiving material.Accordingly, the light-sensitive material is preferably in the form of aroll film for these continuous operations. The light-sensitive materialin the form of the roll film should have a sufficient mechanicalstrength and heat conduction fro these continuous operations. Therefore,a polymer film support is preferably used, since the polymer film has asufficient mechanical strength (such as tensile strength, elasticity andhardness). The thickness of the polymer film is preferably not more than50 μm as is mentioned above. If the thickness is more than 50 μm, theefficiency of heat conduction is lowered and a long development time isrequired. The thickness of the polymer film is preferably not less than10 μm, since the mechanical strength of the film is lowered when thefilm has a thickness of less than 10 μm.

An undercoating layer is preferably provided on the polymer support. Ametal (e.g., aluminum) film is also preferably evaporated onto thepolymer support. A polymer film having a thickness of not more than 50μm onto which an aluminum film is evaporated is a particularly preferredsupport of the present invention.

Optionally employable components contained in a light sensitive layerand optional layers included in a light-sensitive material are describedbelow. The binder employable for the light-sensitive material can beincluded in the light-sensitive layer singly or in combination. Awater-soluble binder is preferably employed. A typical water-solublebinder is transparent or semi-transparent one, of which examples includenatural substances such as gelatin, gelatine derivatives, cellulosederivatives, starch and gum arabic; and synthetic polymer substancessuch as polyvinyl alcohol, polyvinyl pyrrolidone and water-solublepolyvinyl compound (e.g., acrylamide polymer). One of the other examplesof synthetic polymer substances is a dispersing polyvinyl compound whichincreases the size-stability of photographic materials in form of latex.

An organometalic salt can be used as an oxidizing agent in combinationwith silver halide in the invention. An organic silver salt is mostpreferably employed. Examples of an organic compound employable forforming such organosilver salt oxidizing agent include benzotriazoles,aliphatic acids and other compounds described in U.S Pat. No. 4,500,626(columns 52-53). Also effectively employable are silver salts ofcarboxylic acids having alkynyl group (e.g., silver phenylpropionate)and acetylene silver salt. The organic silver salts can be used singlyor in combination of two or more kinds.

The above-mentioned organic silver salt can be used in combination witha light-sensitive silver halide in an amount of 0.01 to 10 mole,preferably 0.01 to 1 mole, per 1 mole of the silver halide. The totalamount of the organic silver salt and the silver halide is generallywithin a range of 1 mg/m² to 10 g/m² in terms of the amount of silvermetal.

The antismudging agent employable for the light-sensitive material ispreferably used in form of solid grains at room temperature. Concreteexamples of the antismudging agent employable for the light-sensitivematerial include starch grains described in U.K. Patent No. 1,232,347,fine powder of polymer U.S. Pat. No. 3,625,347, microcapsules containingno color developing agent described in U.K. Patent No. 1,235,991, finepowder of cellulose described in U.S. Pat. No. 2,711,357 and inorganicgrains such as talc, kaolin, bentonite, pagodite, zinc oxide, titaniumoxide, alumina. A mean grain size of the above-mentioned grains ispreferably within the range of 3 to 50 μm, more preferably 5 to 40 μm,in terms of volume mean diameter. It is effective that the size of thegrain is larger than that of the microcapsule.

Various image formation accelerators is employable for thelight-sensitive material.

Image formation accelerators have the functions such as 1) acceleratingthe transfer of a base or a base precursor, 2) accelerating the reactionof a reducing agent and a silver salt, 3) accelerating the passivatingreaction of coloring substances by polymerization. From a viewpoint ofphysical chemistry concerning the functions, the image formationaccelerators can be classified into base or base precursor nucleophiliccompounds, oils, heat solvents, surface active agents, compounds havinginteractions with silver or silver salts, compounds having deoxidizationfunction and other compounds. However, these substances generally havecomplex functions, so each of them usually has some acceleration effectsdescribed above. In the system wherein the polymerizable compound ispolymerized within the area where a latent image of silver halide is notformed, a thermal polymerization initiator or a photopolymerizationinitiator may be contained in the light-sensitive layer. Further, thethermal polymerization initiator or the photopolymerization initiatormay also be contained in the image-receiving material to harden thetransferred image.

Examples of the thermal polymerization initiator include azo compounds,organic peroxides, inorganic peroxides and sulfinic acids. The thermalpolymerization initiator is described in "Addition Polymerization andRing Opening Polymerization", pp.6-18, edited by the Editorial Committeeof High Polymer Experimental Study of the High Polymer Institute,published by Kyoritsu Shuppan (1983).

Examples of the photopolymerization initiator include benzophenones,acetophenones, benzoins and thioxanthones. The photopolymerizationinitiator is described in "Ultraviolet Ray Hardening System", pp.63-147,edited by the General Technical Center (1989).

Various surface active agents are employable for the light-sensitivematerial for various purpose, such as aiding the coating process,increasing facility of peeling off, increasing slipperiness, preventingelectrification and accelerating development.

An antistatic agent is employable for the light-sensitive materials inorder to prevent electrifying. Antistatic agents are described inResearch Disclosure Vol. 176, No. 17643, pp. 27 (November 1978).

In order to prevent halation and irradiation, a dye or a pigment may beadded to the light-sensitive layer of the light-sensitive materials.

The microcapsules may contain a coloring matter having a property ofbeing decolored by heating or irradiation with light. The coloringmatter having a property of being decolored by heating or irradiationwith light can play the role corresponding to yellow filter in theconventional silver salt photography system.

In the case that a solvent of a polymerizable compound is used for thelight-sensitive material, the solvent is preferably contained inmicrocapsules other than those containing polymerizable compound. Silverhalide grains adsorbing water soluble vinyl polymer can also beemployed.

Various development terminators can be employable for thelight-sensitive materials in order to obtain an image of constantquality independent of the temperature and the process of developmenttreatment.

In the specification, "a development terminator" means a compound whichinteracts with silver or silver salts to inhibit the development, or acompound which neutralizes or reacts with a base to reduce the baseconcentration in order to terminate the development. Concrete examplesof a development terminator include a acid precursor which emits an acidby heating, an electrophilic compound which substitutes a chlorine atomexisting together with by heating, a nitrogen including heterocycliccompound, a mercapto compound and a precursor thereof.

Examples of an optional layer provided in a light-sensitive materialinclude an image-receiving layer, a heating layer, an anti-electrifyinglayer, an anti-curling layer, a peeling layer, a cover sheet or aprotective layer, a layer containing a base or a base precursor, a layerof base barrier and an anti-halation layer (a coloring layer). When thelight-sensitive material is used, the image may be formed on theabove-mentioned image-receiving layer provided on the light-sensitivematerial, instead of using an image-receiving material (describedlater). An image-receiving layer provided on the light-sensitivematerial can have the same constitution as that on an image-receivingmaterial. The detail of the image-receiving layer is described below.

In the image formation using the light-sensitive material, an image canbe formed on an image-receiving material. The image-receiving materialis described below.

The image-receiving material may comprise a support alone. However, animage-receiving layer is preferably provided on the support.

Examples of the materials used for the preparation of the support of theimage-receiving material include glasses, ordinary papers, fine paper,baryta paper, coat paper, cast-coat paper, synthetic papers, metals andanalogues thereof, various films made of polyester, polyethylene,polypropylene, acetyl cellulose, cellulose ester, polyvinyl acetal,polystyrene, polycarbonate, polyethylene terephthalate and polyimide,and papers laminated with resin or polymer (e.g., polyethylene). In thecase that a porous material such as paper is used as a support of animage-receiving material, the surface of the material preferably has acertain smoothness.

The image-receiving layer of an image-receiving material comprises awhite pigment, a binder and other additives. Examples of the whitepigment employable for an image-receiving layer include inorganic whitepigments such as oxides (e.g., silicon oxide, titanium oxide, zincoxide, magnesium oxide and aluminium oxide), salts of alkaline earthmetals (magnesium sulfate, barium sulfate, calcium sulfate, magnesiumcarbonate, barium carbonate, calcium carbonate, calcium silicate,magnesium hydroxide, magnesium phosphate and magnesiumhydrogenphosphate), aluminium silicate, aluminum hydroxide, zincsulfide, various kinds of clay, talc, kaolin, zeolite, acid clay,soluble clay and glass; organic white pigments such as polyethylene,polystyrene, benzoguanamine resin, urea-formalin resin,melamine-formalin resin and polyamide resin. The white pigmentabove-described can be used in the invention singly or in combination. Awhite pigment which can absorb a high amount of a polymerizable compoundis preferably used.

The mean grain size of the white pigment is within a range of 0.1 to 20μm, preferably 0.1 to 10 μm. The amount of the pigment is in the rangeof 0.1 to 60 g, preferably 0.5 to 30 g. The weight ratio of the whitepigment to a binder preferably is in the range of 0.01 to 0.4, and morepreferably 0.03 to 0.3.

As the binder, a water-soluble polymer, a polymer latex and a polymersoluble in an organic solvent are employed.

Examples of the water-soluble polymer include cellulose derivatives suchas carboxymethylcellulose, hydroxyethylcellulose and methylcellulose;proteins such as gelatin, phthalated gelatin, casein and egg albumin;starch and its derivatives such as dextrin and etherificated starch;synthetic polymers such as polyvinyl alcohol, partial acetal ofpolyvinyl alcohol, poly-N-vinyl pyrolidone, polyacrylic acid,polymethacrylic acid, polyacrylamide, polyvinyl imidazole, polyvinylpirazole and polystyrenesulfonic acid; and others such as locust beangum, pullulan, gum arabic and sodium alginate.

Examples of the polymer latex include styrene-butadiene copolymer latex,methyl methacrylate-butadiene copolymer latex, polyacrylate latex,polymethacrylate latex, acrylate-methacrylate copolymer latex andethylene-vinyl acetate copolymer latex.

Examples of the polymer soluble in an organic solvent include polyesterresin, polyurethane resin, polyvinyl chloride resin andpolyacrylonitrile resin.

The binders can be used singly or in combination. A combination of twoor more binders can be employed to cause a phase separation in the imagerecording layer.

The image-receiving layer may further contain various components otherthan the white pigment and the binder.

For example, a color developer can be contained in the image-receivinglayer in the case that a color formation system using a color former andthe color developer is used. Examples of the color developer includephenols, organic acids and salts, and esters. Zinc salt of an salicylicacid derivative is preferred in the case that a leuco dye is used as acolor image forming substance (color former).3,5-di-α-methylbenzylsalicylic acid is particularly preferred.

The color developer is preferably contained in the im. age-receivinglayer in a coating amount of 0.1 to 50 g/m², and more preferably 0.5 to20 g/m².

A thermoplastic compound may be contained in the image recording layer.In the case that the thermoplastic compound is contained in the imagerecording layer, the image recording layer itself is preferably composedof an agglomerate of fine particles of the thermoplastic compound (i.e.,granular thermoplastic compound). The image recording layer having thisconstitute has such advantages that the formation of a transferred imagecan be readily done and a glossy image can be obtained under heatingafter the image formation. There is no specific limitation on thethermoplastic compounds, and any known thermoplastic resins (plastics)and waxes can be employed. The glass transition point of thethermoplastic resin or the melting point of the wax preferably is nothigher than 200° C. A photopolymerization initiator or a thermalpolymerization initiator may be contained in the image recording layer.The photopolymerization initiator or the thermal polymerizationinitiator can be incorporated into the image recording layer to cure theunpolymerized polymerizable compound.

The image formation using the light-sensitive material is describedbelow.

Various exposure means can be employed in the imagewise exposure, and ingeneral, the light-sensitive material is imagewise exposed to aradiation to obtain a latent image of the silver halide. The kind oflight source or the amount of light employed in the exposure can beselected depending on a light-sensitive wavelength (or intensifiedwavelength in the case of spectral sensitization) of the silver halideand a sensitivity of the light-sensitive material.

The examples of the radiation include natural light, ultraviolet light,visible light and infrared light. A high energy radiation such as X-ray,γ-ray and electron beam is also available. However, the light sourcedoes not need to be high energy. Examples of the light source include afluorescent lamp, a tungsten lamp, a halogen lamp, a xenon flash lamp,various lasers (e.g., a gas laser, a solid laser, a chemical laser and asemiconductor laser), a light emission diode, a plasma emitting tube andFOT.

In the case that a full color image is formed, the light-sensitivematerial contains two or more microcapsules which are different fromeach other with respect to the spectral sensitivity. Accordingly, thelight-sensitive material is exposed to two or more spectral lights toform a full color image. In this case, a light source emitting two ormore lights is available. Further, a combination of two or moremonochromatic light sources is also available.

The light source should be selected in consideration of thelight-sensitive wavelength as is mentioned above. Further, it ispreferably considered whether the image information is an electricalsignal or not (digital or analog). The processing speed of the system,the size of the image recording apparatus and the electric power of theapparatus are also important factors of the light source.

In the case that the image information is not an electrical signal, asubject such as a landscape, a portrait is directly photographed, anoriginal image is directly copied, or a positive such as a reversal filmis exposed to light. In this case, exposure devices for a camera, aprinter, an enlarging apparatus and a copying machine are available. Atwo-dimensional image can be exposed to light by one shot using theseexposure device. Further, the image can also be scanned through a slit.An original image can be enlarged or reduced. In this case, afluorescent lamp or a tungsten lamp is a preferred light source.However, a monochromatic light such as a laser is also available wheretwo ore more light are used in combination. In the case that the imageinformation is an electrical signal, two or more monochromatic lightssuch as a light emission diode or a laser can be used in combination asa light source. The combination is determined in consideration of thespectral sensitivity of the light-sensitive material. Further, variousdisplay devices (CRT, liquid crystal display, electroluminescencedisplay, electrochromic display and plasma display) are also available.In this case, the image information is an image signal such as aobtained by a video camera or an electron still camera, a televisionsignal, a signal obtained by scanning an original image, and a signalstored in a recording material such as a magnetic tape or disk.

In the case of the exposure of a color image, two or more monochromaticlights are used in combination in consideration of the spectralsensitivity of the light-sensitive material. In this case, two or morelight sources such as LED, a laser and a fluorescent lamp may be used incombination. The spectral sensitivity of the light-sensitive materialusually contains R (Red), G (Green) and B (Blue). Light sources of UV(Ultraviolet) and IR (Infrared) have also recently been available. Inaddition to the combination of R, G and B, examples of the combinationof the spectral sensitivity include (G, R, IR), (R, short wave IR, longwave IR), (short wave UV, medium wave UV, long wave UV) and (UV, B, G).A combination of different light sources such as two kinds of LED and alaser is available. A light emitting tube or element can be used in ascanning exposure with respect to individual colors. Arrays such as aLED array, a liquid crystal shutter array and a magneto-optical elementshutter array can be used to increase the speed of the exposure.

The display devices such as CRT include a monochromatic device and acolor device. The monochromatic device may form a color image in thecase that a filter and a multiple exposure are employed. A conventionaltwo-dimensional display device can be used as a one-dimensional devicesuch as FOT. In the case that the display device and a scanner are usedin combination, the displayed image can be divided into two or moreparts.

In the second embodiment of the present invention using aphotopolymerization initiator, a polymerizable compound is polymerizedby the initiator within the exposed are.

In the first embodiment of the invention using silver halide and areducing agent, the light-sensitive material is heated simultaneouslywith or after imagewise exposure. The light-sensitive material ispreferably heated from the side of the support.

Heating in the heat development process can be conducted in variousknown manners. For example, a heating layer which is arranged on thelight-sensitive material can be used as the heating means. Further, thelight-sensitive material can be heated on a hot plate, an iron or a heatroller. Furthermore, the material can be heated between a heat rollerand a belt.

The whole surface of the light-sensitive material can be heated by aheater which is larger than the light-sensitive material. Thelight-sensitive material can also be heated by scanning the materialwith a small heater (e.g., hot plate, heat roller, heat drum).

Further, the light-sensitive material can be heated though the materialis not in contact with a heater. For example, the light-sensitivematerial may be heated with an electromagnetic wave, an infrared ray ora hot air.

In the case that the light-sensitive material is heated from the side ofthe support, the side of the light sensitive layer is usually open tothe air. However, the side of the layer may be covered with an adiabaticmaterial to maintain the heating temperature. In this case, it isnecessary to carefully handle the adiabatic material. If the adiabaticmaterial is pressed on the light-sensitive material at a high pressure(10 kg/cm² or more), the microcapsules contained in the light-sensitivelayer tend to be ruptured.

After the light-sensitive material is imagewise exposed to light, thelight-sensitive material is heated preferably at an interval of 0.1second or more. The heating time is preferably in the range of 0.1 to 5seconds, and more preferably in the range of 0.1 to 3 seconds. Theheating temperature usually ranges from 60° C. to 250° C., preferablyfrom 80° C. to 180° C.

In the above-described heat development process, the polymerizablecompound is polymerized within the area where a latent image of thesilver halide has been formed or the area where a latent image of thesilver halide has not been formed. In the case that a polymerizationinhibitor is formed by a reaction of a reducing agent within the areawhere a latent image of silver halide, the polymerizable compound withinthe area where a latent image of the silver halide has not been formedis polymerized by a thermal polymerization initiator or aphotopolymerization initiator. The thermal polymerization initiator orthe photopolymerization initiator is preferably contained in thelight-sensitive layer, and more preferably contained in themicrocapsules. After the heat development process, the light-sensitivematerial may be heated in the presence of the thermal polymerizationinitiator, or irradiated with light in the presence of thephotopolymerization initiator.

A color image can be obtained on an image-receiving material by pressingthe light-sensitive material on the image-receiving material to transferthe unpolymerized polymerizable compound with the color image formingsubstance to the image-receiving material.

For applying a pressure to the light-sensitive material and theimage-receiving material, any known pressing methods can be employed.

For example, the light-sensitive material and the image-receivingmaterial are sandwiched between press plates such as a presser ortransferred using a pressure roller such as a nip roll, to apply apressure to them. A dot-impact pact device can be also employed tointermittently give a pressure to them. Otherwise, a pressure may beapplied to the light-sensitive material and the image-receiving materialby spraying a high-pressure air by means of an air gun or using aultrasonic wave-generating device or a piezoelectric element.

The light-sensitive material and the image-receiving material arepreferably pressed at a pressure of not less than 500 kg/cm², and morepreferably not less than 800 kg/cm². It is particularly preferred thatthe materials are pressed while heating. When the materials are heated,an image can be transferred a pressure of not more than 300 kg/cm².

The light-sensitive material of the invention can be used for colorphotography, printing and copy (e.g., computer-graphic hard copy andxerox copy). The present invention provides a compact and inexpensiveimage forming system such as a copying machine and a printer.

The present invention is further described by the following examples,but those examples are given by no means to restrict the invention.

EXAMPLE 1

Preparation of Silver Halide Emulsion (EB-1)

In distilled water was added 24 g of limed inert gelatin, and theresulting the mixture was stirred at 40° C. for 1 hour to dissolvegelatin in water. To the solution was added 13 g of sodium chloride. Thesolution was adjusted to pH 3.2 using 1N sulfuric acid.

To the solution were added the solutions (I) and (II) at 60° C. for 45minutes keeping pAg of 8.5 by a control double jet method. After theaddition, the mixture was adjusted to pH 6.0 using 1N sodium hydroxide.To the mixture were added 4.8 mg of phenol and 480 mg of the sensitizingdye (SB-1). After 20 minutes, to the mixture was added 100 g of aqueoussolution containing 4.1 g of potassium iodide at the same feed rate over3 minutes.

Solution (I)

120 g of AgNO₃ in 550 ml of distilled water

Solution (II)

85 g of KBr in 550 ml of distilled water ##STR5##

To the emulsion was added 1.1 g of a copolymer of isobutylene/monosodiummaleate copolymer for sedimentation. After the emulsion was washed withwater for desalting, 6 g of limed gelatin was dissolved in the emulsion.To the emulsion was further added 3 ml of 72% aqueous solution ofphenol. The emulsion was adjusted to pH 6.2.

Thus, 550 g of a monodispersed tetradecahedral silver iodobromideemulsion (EB-1) (mean grain size: 0.24 μm, distribution coefficient:20%) was prepared.

Preparation of Silver Halide Emulsion (EG-1)

A monodispersed silver iodobromide emulsion (EG-1) (yield: 550 g, meangrain size: 0.18 μm, distribution coefficient: 22%) was prepared in thesame manner as in preparation of the silver halide emulsion (EB-1)except that the addition time for the solutions (I) and (II) was changedfrom 45 minutes to 15 minutes and 450 mg of the sensitizing dye (SG-1)was used in place of the sensitizing dye (SB-1). ##STR6##

Preparation of Silver Halide Emulsion (ER-1)

A monodispersed silver iodobromide emulsion (ER-1) (yield: 550 g, meangrain size: 0.18 μm, distribution coefficient: 22%) was prepared in thesame manner as in preparation of the silver halide emulsion (EG-1)except that 450 mg of the sensitizing dyes (SR-1) and (SR-2) were usedin place of the sensitizing dye (SG-1). ##STR7##

Preparation of solid Dispersion (KB-1)

In a 300 ml dispersion container were placed 110 g of 5.4% aqueoussolution of limed gelatin, 20 g of 5% aqueous solution of polyethyleneglycol (average molecular weight: 2,000), 70 g of the base precursor(BG-1) and 200 ml of glass beads having diameters in the range of0.5-0.75 mm. The resulting mixture was stirred at 3,000 r.p.m. forminutes using Dynomill. The mixture was adjusted to pH 6.5 using 2Nsulfuric acid to obtain a solid dispersion (KB-1) of the base precursor(43) having a grain size of not more than 1.0 μm. ##STR8##

Preparation of Pigment Dispersion (GY-1)

To 255 g of the polymerizable compound (MN-2) (Alonix M310 availablefrom Toagosei chemical Industry Co., Ltd.) was added 45 g of MicrolithYellow 4GA (tradename, available from Ciba-Geigy). The resulting mixturewas stirred for 1 hour at 5,000 r.p.m. using Eiger Motor Mill (tradenameof Eiger Engiierring) to obtain a pigment dispersion (GY-1). ##STR9##

Preparation of Pigment Dispersion (GM-1)

To 255 g of the polymerizable compound (MN-2) was added 45 g ofMicrolith Red 3RA (tradename, available from Ciba-Geigy). The resultingmixture was stirred for 1 hour at 5,000 r.p.m. using Eiger motor mill(produced by Eiger Engineering Co., Ltd.) to obtain a pigment dispersion(GM-1).

Preparation of Pigment Dispersion (GC-1)

To 255 g of the polymerizable compound (MN-1) (Kayarad R604 availablefrom Nippon Kayaku Co., Ltd.) were added 45 g of copper phthalocyanine(C.I.: Pigment 15), 1.13 g of Solsperse 5000 (tradename of ICI) and 3.37g of Solsperse (tradename of ICI). The mixture was stirred for 1 hour at5,000 r.p.m. using Eiger Motor Mill (tradename of Eiger Enginierring) toobtain a pigment dispersion (GC-1). ##STR10##

Preparation of Light-sensitive Composition (PB-1)

To 45 g of the pigment dispersion (GY-1) were added 9 g of 20 weight %solution of the copolymer (1P-1) in the solvent (SV-1), 2.3 g of (RD-1),6.2 g of (RD-3), 1 g of 0.5% solution of (FF-3) in (SV-1) and 5 g of(ST-1) to prepare an oily solution. ##STR11##

To the resulting solution were added 3.8 g of the silver halide emulsion(EG-1) and 24 g of the solid dispersion (KB-1), and the resultingmixture was stirred at 10,000 r.p.m. for 5 minutes at 60° C. using adissolver of 40 φ to obtain a light-sensitive composition (PG-1) in theform of a W/O emulsion.

Preparation of Light-sensitive Composition (PG-1)

To 45 g of the pigment dispersion (GC-1) were added 9 g of 20 weight %solution of the copolymer (1P-1) in (SV-1), 2.3 g of (RD-1), 3.1 g of(RD-2), 1 g of 0.5% solution of (FF-3) in (SV-1) and 5 g of (ST-1) toprepare an oily solution.

To the resulting solution were added 3.8 g of the silver halide emulsion(EG-1) and 24 g of the solid dispersion (KB-1), and the resultingmixture was stirred at 10,000 r.p.m. for 5 minutes at 60° C. using adissolver of 40 φ to obtain a light-sensitive composition (PG-1) in theform of a W/O emulsion.

Preparation of Light-sensitive Composition (PR-1)

To 45 g of the pigment dispersion (GC-1) were added 9 g of 20 weight %solution of the copolymer (1P-1) in (SV-1), 2.3 g of (RD-1), 6.2 g of(RD-2), 1 g of 0.5% solution of (FF-3) in (SV-1) and 5 g of (ST-1) toprepare an oily solution.

To the resulting solution were added 3.8 g of the silver halide emulsion(EG-1) and 24 g of the solid dispersion (KB-1), and the resultingmixture was stirred at 10,000 r.p.m. for 5 minutes at 60° C. using adissolver of 40 φ to obtain a light-sensitive composition (PG-1) in theform of a W/O emulsion. ##STR12##

To

Preparation of Microcapsules Dispersion (CB-1)

To 4 g of 15% aqueous solution of the polymer (2P-1) was added 36 g ofwater. The mixture was adjusted to pH 5.0 using sulfuric acid. To themixture was further added 60 g of 10% aqueous solution of the polymer(2P-2). The resulting mixture was stirred at 60° C. for 30 minutes. Themixture was added to the light-sensitive composition (PB-1), and theresulting mixture was stirred at 7,000 r.p.m. for 20 minutes at 50° C.using a dissolver of 40 φ to obtain a WOW emulsion.

To 250 g of the emulsion was added 2,250 g of distilled water, and themixture was stirred for 15 minutes using a stirrer. The mixture was leftfor 1 hour to precipitate the emulsion. Then, 2,400 g of the supernatantwas removed. To the residue was added 50 g of 6% aqueous solution of thepolymer (2P-2). The mixture was stirred again to obtain a W/0/Wemulsion.

Independently, to 31.5 g of melamine were added 52.2 g of 37% aqueoussolution of formaldehyde and 170.3 g of water, and the resulting mixturewas stirred at 60° C. for 30 minutes to obtain a transparentmelamine-formaldehyde precondensate. To the above-prepared WOW emulsionat 40° C. was added 25 g of the precondensate. The mixture was stirredat 1,200 r.p.m. using a propeller wing, and was adjusted to pH 5.0 using2N sulfuric acid. The mixture was then heated to 70° C. for 30 minutes,and stirred for 30 minutes. Further, to the mixture was added 10.3 g of40% aqueous solution of urea, and the mixture was adjusted to pH 3.5using 2N sulfuric acid, and then stirred at 70° C. for 40 minutes.

The mixture was cooled to 40° C. To the mixture was added 7.5 g of 2.5%aqueous solution of K-carrageenan. The resulting mixture was stirred for10 minutes, and adjusted to pH 6.5 using 2N aqueous solution of sodiumhydroxide to prepare a light-sensitive microcapsule dispersion (CB-1).The dispersion was immediately placed and stored at 8° C. in arefrigerator.

Polymer (2P-1)

Potassium polyvinylbenzenesulfinate

Polymer (2P-2)

Polyvinyl pyrrolidone (K-90 available from GAF)

Preparation of Microcapsule Dispersion (CG-1)

To 4 g of 15% aqueous solution of the polymer (2P-1) was added 26 g ofwater. The mixture was adjusted to pH 5.0 using sulfuric acid. To themixture was further added 70 g of 10% aqueous solution of the polymer(2P-2). The resulting mixture was stirred at 60° C. for 30 minutes. Themixture was added to the light-sensitive composition (PG-1), and theresulting mixture was stirred at 5,000 r.p.m. for 20 minutes at 60° C.using a dissolver of 40 φ to obtain a W/O/W emulsion.

To 250 g of the emulsion was added 1,250 g of distilled water, and themixture was stirred for 15 minutes using a stirrer. The mixture was leftfor 1 hour to precipitate the emulsion. Then, 1,400 g of the supernatantwas removed. To the residue was added 50 g of 5% aqueous solution of thepolymer (2P-2). The mixture was stirred again to obtain a W/O/Wemulsion.

Then, a light-sensitive microcapsule dispersion (CG-1) was prepared inthe same manner as in the preparation of the dispersion (CB-1). Thedispersion was immediately placed and stored at 8° C. in a refrigerator

Preparation of Microcapsule Dispersion (CR-1)

To 4 g of 15% aqueous solution of the polymer (2P-1) was added 36 g ofwater. The mixture was adjusted to pH 5.0 using sulfuric acid. To themixture was further added 60 g of 10% aqueous solution of the polymer(2P-2). The resulting mixture was stirred at 60° C. for 30 minutes. Themixture was added to the light-sensitive composition (PR-1), and theresulting mixture was stirred at 5,000 r.p.m. for 20 minutes at 50° C.using a dissolver of 40 φ to obtain a W/O/W emulsion.

To 250 g of the emulsion was added 750 g of distilled water, and themixture was stirred for 15 minutes using a stirrer. The mixture was leftfor 1 hour to precipitate the emulsion. Then, 900 g of the supernatantwas removed. To the residue was added 50 g of 6% aqueous solution of thepolymer (2P-2). The mixture was stirred again to obtain a W/O/Wemulsion.

Then, a light-sensitive microcapsule dispersion (CG-1) was prepared inthe same manner as in the preparation of the dispersion (CB-1). Thedispersion was immediately placed and stored at 8° C. in a refrigerator.

Preparation of Light-sensitive Material (101)

The light-sensitive microcapsule dispersions (CB-1), (CG-1) and (CR-1)were stored for 2 days at 8° C. in a refrigerator. Then, 24 g of (CB-1),36 g of (CG-1) and 57.6 g of (CR-1) were heated to 40° C. withoutstirring to obtain a mixture. To the mixture were added 0.5 g of thesurface active agent (WW-1), 1.3 g of 10% aqueous solution of thesurface active agent (WW-2) and 25 g of 10% aqueous solution ofcarboxylated polyvinyl alcohol (tradename: PVA KL318, available fromKuraray Co., Ltd.). The resulting mixture was stirred at 40° C. for 10minutes, and filtered through a cloth of 44 μm mesh to prepare a coatingsolution. ##STR13##

An aluminum film is evaporated onto a polyethylene terephthalate film(thickness: 25 μm) to prepare a support. The coating solution was coatedover the aluminium film of the support in an amount of 131 ml/m²according to an extrusion method, and the coated layer of the solutionwas dried at 60° C. to prepare a light-sensitive material (101). Thematerial was rolled up (inside: coated layer) at 25° C. and at 55%relative humidity. The rolled material was preserved in amoistureproofing bag laminated with aluminum at 25° C. and at 55%relative humidity.

Preparation of Image-receiving Material (RS-1)

A mixture of 240 g of calcium carbonate (tradename: PC700, availablefrom Shiraishi Industrial Co., Ltd.), 5.6 g of a surface active agent(poize 520, available from Kao Co., Ltd.) and 354.4 ml of water wasmixed and stirred at 8,000 r.p.m. for 3 minutes using a dispersingdevice (tradename: Ultradisperser LK-41, available from Yamato ScienceCo., Ltd.). To 52 g of the resulting dispersion was added 34.5 g of 10%aqueous solution of polyvinyl alcohol (tradename: PVA-17, available fromKuraray Co., Ltd.). To the mixture were further added 4 ml of 1% aqueoussolution of the surface active agent (WW-3) and 22 ml of water toprepare a coating solution for an image-receiving layer. ##STR14##

The coating solution was uniformly coated over a paper having a basisweight of 80 g/m² (i.e., a paper having a fiber length distribution[defined by JIS-P-8207] in which the sum of weight percent of 24 meshresidue and 42 mesh residue is within a range of 30-60%, as described inJapanese Patent Provisional Publication No. 63(1988)-86239) in an amountof 65 ml/m², and the coated layer of the solution was dried at 60° C. toprepare an image-receiving material (RS-1).

Image Formation and Evaluation Thereof

An image was formed on the image-receiving material (RS-1) using thelight-sensitive material (101) according to the following manner at 25°C. and at 50% relative humidity.

The light-sensitive material was taken out of the moistureproofing bag,and was exposed to light at 20,000 lux and color temperature of 3100° K.for 1 second using a halogen lamp through a wedge in which thetransmission density is continuously changed from 0 to 4.0, an ND filterhaving density of 1.0 and CC filters of yellow and magenta (produced byFuji Photo Film Co., Ltd.) for adjusting a gray balance. After 10seconds, the light sensitive material was heated on a hot plate from theside of the support for 1.5 second at 150° C. using a heat developmentapparatus exhausting a hot air.

The light-sensitive material was superposed on the image-receivingmaterial (RS-1) in such a manner that the light-sensitive layer facedthe image-receiving layer, and they were passed through a pressureroller (diameter: 3 cm) having a pressure of 1,200 kg/cm² at speed of 2cm/second.

The image-receiving material was immediately removed from thelight-sensitive material. A clear positive image was formed on theimage-receiving material. The maximum and minimum densities of the imagewere measured using R-Rite 310. The maximum density was 1.22, and theminimum density was 0.09.

COMPARISON EXAMPLE 1 Preparation of Microcapsule Dispersion (CB-2)

A light-sensitive microcapsule dispersion (CB-2) was prepared in thesame manner as in preparation of the dispersion (CB-1) in Example 1except that 7.5 g of distilled water was used in place of 7.5 g of 2.5%aqueous solution of K-carrageenan. The dispersion was immediately placedand stored at 8° C. in a refrigerator.

Preparation of Microcapsule Dispersion (CG-2)

A light-sensitive microcapsule dispersion (CG-2) was prepared in thesame manner as in preparation of the dispersion (CG-1) in Example 1except that 7.5 g of distilled water was used in place of 7.5 g of 2.5%aqueous solution of K-carrageenan. The dispersion was immediately placedand stored at 8° C. in a refrigerator.

Preparation of Microcapsule Dispersion (CR-2)

A light-sensitive microcapsule dispersion (CR-2) was prepared in thesame manner as in preparation of the dispersion (CR-1) in Example 1except that 7.5 g of distilled water was used in place of 7.5 g of 2.5%aqueous solution of K-carrageenan. The dispersion was immediately placedand stored at 8° C. in a refrigerator.

Preparation of light-sensitive material (102)

The light-sensitive microcapsule dispersions (CB-2), (CG-2) and (CR-2)were stored for 2 days at 8° C. in a refrigerator. The microcapsuleswere deposited on the bottom of the vessels containing the dispersions.Therefore, the dispersions were heated to room temperature and stirredusing a plastic bar. Then, 24 g of (CB-1), 36 g of (CG-1) and 57.6 g of(CR-1) were mixed to obtain a mixture. To the mixture were added 0.5 gof the surface active agent (WW-1), 1.3 g of 10% aqueous solution of thesurface active agent (WW-2) and 25 g of 10% aqueous solution ofcarboxylated polyvinyl alcohol (tradename: PVA KL318, available fromKuraray Co., Ltd.). The resulting mixture was stirred at 40° C. for 10minutes, and filtered through a cloth of 44 μm mesh to prepare a coatingsolution. The filtration required a long time, and a precipitation(aggregation of the microcapsules) remained on the cloth.

A light-sensitive material (102) was prepared in the same manner as inpreparation of the material (101) in Example 1 using the above-preparedcoating solution. The material was rolled up (inside: coated layer) at25° C. and at 55% relative humidity. The rolled material was preservedin a moistureproofing bag laminated with aluminum at 25° C. and at 55%relative humidity.

Image Formation and Evaluation Thereof

An image was formed and evaluated in the same manner as in Example 1. Asthe results, the maximum density was 1.03, and the minimum density was0.16.

The maximum density is low compared with the result of Example 1, sincesome of the microcapsule were precipitated (while the microcapsuledispersion was stored) and removed by the filtration.

The minimum density is high compared with the result of Example 1, sincesome of the microcapsule were destroyed when the microcapsule dispersionwas stirred to disperse the precipitated microcapsules again.

It is apparent from the results of Example 1 and Comparison Example 1that the light-sensitive material pre pared according to the presentinvention forms a clear image having a high maximum density and a lowminimum density, though the material is prepared by using a storedmicrocapsule dispersion.

EXAMPLE 2 Preparation of Microcapsule Dispersion (CB-3)

A light-sensitive microcapsule dispersion (CB-3) was prepared in thesame manner as in preparation of the dispersion (CB-1) in Example 1except that 150 g of the W/O/W emulsion was used without addition ofwater, precipitation of the emulsion and removal of the supernatant.

Preparation of Microcapsule dispersion (CG-3)

A light-sensitive microcapsule dispersion (CG-3) was prepared in thesame manner as in preparation of the dispersion (CG-1) in Example 1except that 150 g of the W/O/W emulsion was used without addition ofwater, precipitation of the emulsion and removal of the supernatant.

Preparation of Microcapsule Dispersion (CR-3)

A light-sensitive microcapsule dispersion (CR-3) was prepared in thesame manner as in preparation of the dispersion (CR-1) in Example 1except that 150 g of the W/O/W emulsion was used without addition ofwater, precipitation of the emulsion and removal of the supernatant.

Preparation of Light-sensitive Material (103)

A light-sensitive material (102) was prepared in the same manner as inpreparation of the material (101) in Example 1 using the above-preparedmicrocapsule dispersions (CB-3), (CG-3) and (CR-3). The material wasrolled up (inside: coated layer) at 25° C. and at 55% relative humidity.The rolled material was preserved in a moistureproofing bag laminatedwith aluminum at 25° C. and at 55% relative humidity.

Image Formation and Evaluation Thereof

An image was formed and evaluated in the same manner as in Example 1. Asthe results, the maximum density was 1.25, and the minimum density was0.12. A linear stain was observed within the minimum density area. Thestain was caused by the destroyed microcapsules.

Evaluation of the Shell of the Microcapsules

The light-sensitive materials (101) and (103) were cut into a piece of2.6 cm×10 cm. The pieces were placed in 10 ml of toluene for 10 minutes.The toluene was filtered, and examined by a liquid chromatography. Asthe results, a very small amount of the polymerizable compound (lessthan 5% of the coated amount) was detected in the piece of the material(101). On the other hand, 20% of the polymerizable compound was detectedin the piece of the material (102). It is apparent from these resultsthat the shell of the microcapsule of the material (101) was tightlyformed around the core (containing the polymerizable compound) comparedwith the material (103).

We claim:
 1. A process for preparation of a light-sensitive materialcomprising a support and a light-sensitive layer which contains silverhalide, a reducing agent and an ethylenically unsaturated polymerizablecompound, said silver halide, said reducing agent and said polymerizablecompound being contained in microcapsules which are dispersed in thelight sensitive layer, wherein the process comprises the steps of:(1)mixing a silver halide emulsion and the reducing agent with thepolymerizable compound to prepare a light-sensitive composition; (2)emulsifying the composition in an aqueous medium to prepare an aqueousemulsion containing droplets of the composition in the aqueous medium;(3) forming a shell around the droplets of the composition contained inthe aqueous emulsion to prepare a microcapsule dispersion whereinmicrocapsules are dispersed in the aqueous medium; (4) coagulating theaqueous medium, to set the microcapsule dispersion; (5) storing the setmicrocapsule dispersion; (6) melting the stored set microcapsuledispersion to prepare a coating solution of the light-sensitive layer;and (7) coating the solution on the support
 2. The process as claimed inclaim 1, wherein the specific gravity of the light-sensitive compositionis more than
 1. 3. The process as claimed in claim 1, wherein theaqueous medium is coagulated by adding an aqueous polymer as a gelationagent to the microcapsule dispersion and cooling the dispersion at thestep (4), and the aqueous medium is melted by heating the dispersion atthe step (6).
 4. The process as claimed in claim 3, wherein the thegelation agent is a polysaccharide.
 5. The process as claimed in claim3, wherein the the gelation agent is used in the microcapsule dispersionin an amount of 0.01 to 10 weight %.
 6. The process as claimed in claim3, wherein the aqueous medium has a gel point at a temperature in therange of 0° C. to 40° C.
 7. The process as claimed in claim 1, whereinthe shell of the microcapsules is made of an amino-aldehyde resin. 8.The process as claimed in claim 7, wherein between the step (2) and (3),the process further contains the steps of:(a) precipitating the dropletsof the light-sensitive composition in the aqueous emulsion; (b) removingat least 50% of a supernatant medium from the droplets; and (c)emulsifying the droplets in an aqueous medium again.
 9. The process asclaimed in claim 1, wherein the light-sensitive composition furthercontains a color image forming substance.
 10. The process as claimed inclaim 1, wherein the light-sensitive composition further contains a baseprecursor.